This is a quick sketch of moving types from Identifier to Places so that we can have flow-sensitive types. The intent isn't to ship this but to quickly explore in order to figure out concrete challenges, to inform a "real" implementation.
Some observations:
* ReactiveScopeDependency/Declaration now need types. We use the type of their identifier currently, so we'd have to populate a type for them instead. But if we do flow-sensitive types, there won't be one obvious correct type to use! Consider a scope that uses `x` twice, once where we can infer its a primitive and one where we can't. We should treat this like phi typing and only infer a precise type for the dep/decl if all references have the same type.
* InferMutableRanges's aliasing logic uses a `DisjointSet<Identifier>` and checks the types for some things (refs in particular). So the obvious approach is to replace that with a `DisjointSet<Place>`. While doing that I was reminded that the way we handle aliasing for phis is kind of weird. We currently delay creating an alias until we know the phi is mutated later, but we don't do the same thing for things like `x = y` (ie we eagerly alias). Switching to paths is a good chance to revisit the aliasing.
* InferTypes gets tricky because we still want different places with the same identifier to get the same type (for now, until we introduce flow-sensitive typing). But every Place has its own type instance. So for now we can basically keep a mapping of IdentifierId to a canonical Type and use this for all the inference. The actual implementation in the PR is messier than that since i started with a variant of flow-sensitive typing and then rolled it back.
For actual flow-sensitive typing (not implemented here) there's a sort of inverse phi situation. Consider a variant of mofeiZ's recent find:
```
function Component({y}) {
let x = makeValue(y);
let result;
if (...cond...) {
result = ...x... // do something with x
} else {
result = ...x... // do something else with x
}
return result;
}
```
If both branches of the if can infer `x` as a number, then it's sound to infer `makeValue(y)` as producing a number. However, if you take away the else branch then it might not be, since now there's a code path (the fallthrough) in which we're not sure of the type. This is just like a phi for variable reassignment, but at the type level. And it's also happening in reverse — the later "operands" (usages of x) flow backwards into the "phi" that is the type of x before the if/else. We'd have to build up a mapping like this and build the appropriate type equations.
ghstack-source-id: 8360182e32
Pull Request resolved: https://github.com/facebook/react/pull/31575
This was a stopgap until InferTypes supported inference of phi types. I implemented that a while back and forgot to clean this up.
ghstack-source-id: 3017b3a89b
Pull Request resolved: https://github.com/facebook/react/pull/31560
This lets us track separately if something was suspended on an Action
using useActionState rather than suspended on Data.
This approach feels quite bloated and it seems like we'd eventually
might want to read more information about the Promise that suspended and
the context it suspended in. As a more general reason for suspending.
The way useActionState works in combination with the prewarming is quite
unfortunate because 1) it renders blocking to update the isPending flag
whether you use it or not 2) it prewarms and suspends the useActionState
3) then it does another third render to get back into the useActionState
position again.
Now that we rely on function context exclusively, let's clean up
`HIRFunction.context` after DCE. This PR is in preparation of #31204,
which would otherwise have unnecessary declarations (of context values
that become entirely DCE'd)
'
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[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
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* __->__ #31202
* #31203
* #31201
* #31200
* #31521
`JSXMemberExpression` is currently the only instruction (that I know of)
that directly references identifier lvalues without a corresponding
`LoadLocal`.
This has some side effects:
- deadcode elimination and constant propagation now reach
JSXMemberExpressions
- we can delete `LoweredFunction.dependencies` without dangling
references (previously, the only reference to JSXMemberExpression
objects in HIR was in function dependencies)
- JSXMemberExpression now is consistent with all other instructions
(e.g. has a rvalue-producing LoadLocal)
'
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/31201).
* #31202
* #31203
* __->__ #31201
* #31200
* #31521
Recursively visit inner function instructions to extract dependencies
instead of using `LoweredFunction.dependencies` directly.
This is currently gated by enableFunctionDependencyRewrite, which needs
to be removed before we delete `LoweredFunction.dependencies` altogether
(#31204).
Some nice side effects
- optional-chaining deps for inner functions
- full DCE and outlining for inner functions (see #31202)
- fewer extraneous instructions (see #31204)
-
---
[//]: # (BEGIN SAPLING FOOTER)
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with [ReviewStack](https://reviewstack.dev/facebook/react/pull/31200).
* #31202
* #31203
* #31201
* __->__ #31200
* #31521
We were previously filtering out `ref.current` dependencies in
propagateScopeDependencies:checkValidDependency`. This is incorrect.
Instead, we now always take a dependency on ref values (the outer box)
as they may be reactive. Pruning is done in
pruneNonReactiveDependencies.
This PR includes a small patch to `collectReactiveIdentifier`. Prior to
this, we conservatively assumed that pruned scopes always produced
reactive declarations. This assumption fixed a bug with non-reactivity,
but some of these declarations are `useRef` calls. Now we have special
handling for this case
```js
// This often produces a pruned scope
React.useRef(1);
```
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/31521).
* #31202
* #31203
* #31201
* #31200
* __->__ #31521
This includes:
- `Interrupted Render`: Interrupted Renders (setState or ping at higher
priority)
- `Prewarm`: Suspended Renders outside a Suspense boundary
(RootSuspendedWithDelay/RootSuspendedAtTheShell)
- `Errored Render`: Render that errored somewhere in the tree (Fatal or
Not) (which may or may not be retried and then complete)
- `Teared Render`: Due to useSyncExternalStore not matching (which will
do another sync attempt)
Suspended Commit:
<img width="893" alt="Screenshot 2024-11-14 at 11 47 40 PM"
src="https://github.com/user-attachments/assets/b25a6a8b-a5e9-4d66-b325-57aef4bf9dad">
Errored with a second recovery attempt that also errors:
<img width="976" alt="Screenshot 2024-11-15 at 12 09 06 AM"
src="https://github.com/user-attachments/assets/9ce52cbb-b587-4f1e-8b67-e51d9073ae5b">
## Summary
This fixes a typo in the error that gets reported when Float errors
while hoisting a style tag that does not contain both `precedence` and
`href`. There was a typo in _conflict_ and the last part of the sentence
doesn't make sense. I assume it wasn't needed since the message already
suggests moving the style tag to the head manually.
It's useful to quickly see where new events are kicking off new
rendering. This uses the new "warning" color (yellow) to do that. This
is to help distinguish it from the purple (secondary color) which is
used for the commit phase which is more of a follow up and it's often
that you have several rerenders within one event which makes it hard to
tell a part where it starts and event otherwise.
For the span marking between previous render within the same event and
the next setState, I use secondary-light (light purple) since it's kind
of still part of the same sequence at that point. It's usually a spawned
render (e.g. setState in useEffect or microtask) but it can also be
sequential flushSync.
I was bothered by that the event name is the only thing that's lower
case so I prefixed it with `Event: ` like the JS traces are.
<img width="1499" alt="Screenshot 2024-11-13 at 7 15 45 PM"
src="https://github.com/user-attachments/assets/0c81c810-6b5d-4fc7-9bc0-d15b53844ade">
It might be a little confusing why our track starts earlier than the JS
one below in the "Main Thread" flamegraph which looks the same. That's
because ours is the start of the event time which is when the click
happens where as the Main Thread one is when the JS event loop gets
around to processing the event.
When you schedule a microtask from render or effect and then call
setState (or ping) from there, the "event" is the event that React
scheduled (which will be a postMessage). The event time of this new
render will be before the last render finished.
We usually clamp these but in this scenario the update doesn't happen
while a render is happening. Causing overlapping events.
Before:
<img width="1229" alt="Screenshot 2024-11-12 at 11 01 30 PM"
src="https://github.com/user-attachments/assets/9652cf3b-b358-453c-b295-1239cbb15952">
Therefore when we finalize a render we need to store the end of the last
render so when we a new update comes in later with an event time earlier
than that, we know to clamp it.
There's also a special case here where when we enter the
`RootDidNotComplete` or `RootSuspendedWithDelay` case we neither leave
the root as in progress nor commit it. Those needs to finalize too.
Really this should be modeled as a suspended track that we haven't added
yet. That's the gap between "Blocked" and "message" below.
After:
<img width="1471" alt="Screenshot 2024-11-13 at 12 31 34 AM"
src="https://github.com/user-attachments/assets/b24f994e-9055-4b10-ad29-ad9b36302ffc">
I also fixed an issue where we may log the same event name multiple
times if we're rendering more than once in the same event. In this case
I just leave a blank trace between the last commit and the next update.
I also adding ignoring of the "message" event at all in these cases when
the event is from React's scheduling itself.
Fixes a bug.
We're supposed to not log "Waiting for Paint" if the passive effect
phase was forced since we weren't really waiting until the paint.
Instead we just log an empty string when we force it to still ensure
continuity.
We should always log the passive phase. This check was in the wrong
place.
In order to make use of the compiler in stable releases (eg React 19 RC,
canary), we need to export the compiler runtime in the stable channel as
well.
## Summary
`@rollup/plugin-typescript` emits a warning while building, hinting that
`outputToFilesystem` defaults to true.
Although "noEmit" is set to `true` for the tsconfig, rollup writes a
`dist/.tsbuildinfo`. That file is then also shipped inside the npm
module and doesn't offer any benefit for library consumers. Setting this
option to false results in the file not being written and thus omitted
from the npm module.
## How did you test this change?
`dist/.tsbuildinfo` is not emitted any more.
Previously we were showing Components inside each lane track but that
meant that as soon as you expanded a lane you couldn't see the other
line so you couldn't get an overview over how well things were
scheduled.
This instead moves all the Components into a single top-level track and
renames the previous one to a "Scheduler" track group.
<img width="1352" alt="Screenshot 2024-11-12 at 8 26 05 PM"
src="https://github.com/user-attachments/assets/590bc6d3-3540-4ee4-b474-5d733b8d8d8d">
That way you can get an overview over what React is working on first and
then right below see which Component is being worked on.
Ideally the "Scheduler" track would be always expanded since each Track
is always just a single row. Now you have to expand each lane to see the
labels but then you're wasting a lot of vertical real estate. There's
currently no option to create this with the Chrome performance.measure
extensions.
<img width="1277" alt="Screenshot 2024-11-12 at 8 26 16 PM"
src="https://github.com/user-attachments/assets/4fc39e35-10ec-4452-ad32-c1c2e6b5e1a8">
In preparation for the next RC, I set this feature flag to true
everywhere. I did not delete the feature flag yet, in case there are yet
more bugs to be discovered.
I also didn't remove the dynamic feature flag from the Meta builds; I'll
let the Meta folks handle that.
Our CI workflows generally cache `**/node_modules` (note the glob, it
caches all transitive node_module directories) to speed up startup for
new jobs that don't change any dependencies. However it seems like one
of our caches got into a weird state (not sure how it happened) where
the `build` directory (used in various other scripts as the directory
for compiled React packages) would contain a `node_modules` directory as
well. This made sizebot size change messages very big since it would try
to compare every single file in `build/node_modules`.
The fix is to ensure we always clean the `build` directory before doing
anything with it. We can also delete that one problematic cache but this
PR is a little more resilient to other weird behavior with that
directory.
This provides less context but skips a lot of noise.
Previously we were including parent components to provide context about
what is rendering but this turns out to be:
1) Very expensive due to the overhead of `performance.measure()` while
profiling.
2) Unactionable noise in the profile that hurt more than it added in
real apps with large trees.
This approach instead just add performance.measure calls for each
component that was marked as PerformedWork (which was used for this
purpose by React Profiler) or had any Effects.
Not everything gets marked with PerformedWork though. E.g. DOM nodes do
not but they can have significant render times since creating them takes
time. We might consider including them if a self-time threshold is met.
Because there is little to no context about the component anymore it
becomes really essential to get a feature from Chrome DevTools that can
link to something with more context like React DevTools.
This reverts commit d3bf32a958 which was
part of #30983
When you have very deep trees this trick can cause the top levels to
skew way too much from the real numbers. Creating unbalanced trees.
The bug should have been fixed in Chrome Canary now so that entries
added later are sorted to go first which should've addressed this issue.
## Summary
We have been getting unhandled `TypeError: Cannot convert object to
primitive value` errors in development that only occur when using
devtools. I tracked it down to `console.error()` calls coming from
Apollo Client where one of the arguments is an object without a
prototype (created with `Object.create(null)`). This causes
`formatConsoleArgumentsToSingleString()` in React's devtools to error as
the function does not defend against `String()` throwing an error.
My attempted fix is to introduce a `safeToString` function (naming
suggestions appreciated) which expects `String()` to throw on certain
object and in that case falls back to returning `[object Object]`, which
is what `String({})` would return.
## How did you test this change?
Added a new unit test.
This readme documents React Server Components from `react-server`
package enough to get an implementer started. It's not comprehensive but
it's a beginning point and crucially adds documentation for the
`prerender` API for Flight.
We've previously failed to land this change due to some internal apps
seeing infinite render loops due to external store state updates during
render. It turns out that since the `renderWasConcurrent` var was moved
into the do block, the sync render triggered from the external store
check was stuck with a `RootSuspended` `exitStatus`. So this is not
unique to sibling prerendering but more generally related to how we
handle update to a sync external store during render.
We've tested this build against local repros which now render without
crashes. We will try to add a unit test to cover the scenario as well.
---------
Co-authored-by: Andrew Clark <git@andrewclark.io>
Co-authored-by: Rick Hanlon <rickhanlonii@fb.com>
## Summary
I'm working to get the main `react-native` package parsable by modern
Flow tooling (both `flow-bundler`, `flow-api-translator`), and one
blocker is legacy `module.exports` syntax. This diff updates files which
are [synced to
`react-native`](https://github.com/facebook/react-native/tree/main/packages/react-native/Libraries/Renderer/shims)
from this repo.
## How did you test this change?
Files were pasted into `react-native-github` under fbsource, where Flow
validates ✅.
Previously, we bailed out on outlining jsx that had children that were
not part of the outlined jsx.
Now, we add support for children by treating as attributes.
Previously, we would skip outlining jsx expressions that had duplicate
jsx attributes as we would not rename them causing incorrect
compilation.
In this PR, we add outlining support for duplicate jsx attributes by
renaming them.
Previously, we'd directly store the original attributes from the jsx
expressions. But this isn't enough as we want to rename duplicate
attributes.
This PR refactors the prop collection logic to store both the original
and new names for jsx attributes in the newly outlined jsx expression.
For now, both the new and old names are the same. In the future, they
will be different when we add support for outlining expressions with
duplicate attribute names.
Recursively collect identifier / property loads and optional chains from
inner functions. This PR is in preparation for #31200
Previously, we only did this in `collectHoistablePropertyLoads` to
understand hoistable property loads from inner functions.
1. collectTemporariesSidemap
2. collectOptionalChainSidemap
3. collectHoistablePropertyLoads
- ^ this recursively calls `collectTemporariesSidemap`,
`collectOptionalChainSidemap`, and `collectOptionalChainSidemap` on
inner functions
4. collectDependencies
Now, we have
1. collectTemporariesSidemap
- recursively record identifiers in inner functions. Note that we track
all temporaries in the same map as `IdentifierIds` are currently unique
across functions
2. collectOptionalChainSidemap
- recursively records optional chain sidemaps in inner functions
3. collectHoistablePropertyLoads
- (unchanged, except to remove recursive collection of temporaries)
4. collectDependencies
- unchanged: to be modified to recursively collect dependencies in next
PR
'
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/31346).
* #31202
* #31203
* #31201
* #31200
* __->__ #31346
* #31199
`enablePropagateScopeDepsHIR` is now used extensively in Meta. This has
been tested for over two weeks in our e2e tests and production.
The rest of this stack deletes `LoweredFunction.dependencies`, which the
non-hir version of `PropagateScopeDeps` depends on. To avoid a more
forked HIR (non-hir with dependencies and hir with no dependencies),
let's go ahead and clean up the non-hir version of
PropagateScopeDepsHIR.
Note that all fixture changes in this PR were previously reviewed when
they were copied to `propagate-scope-deps-hir-fork`. Will clean up /
merge these duplicate fixtures in a later PR
'
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/31199).
* #31202
* #31203
* #31201
* #31200
* #31346
* __->__ #31199
All dependencies and declarations of a reactive scope can be reordered
to scope start/end. i.e. generated code does not depend on conditional
short-circuiting logic as dependencies are inferred to have no side
effects.
Sorting these by name helps us get higher signal compilation snapshot
diffs when upgrading the compiler and testing PRs
Move environment config parsing for `inlineJsxTransform`,
`lowerContextAccess`, and some dev-only options out of snap (test
fixture). These should now be available for playground via
`@inlineJsxTransform` and `lowerContextAccess`.
Other small change:
Changed zod fields from `nullish()` -> `nullable().default(null)`.
[`nullish`](https://zod.dev/?id=nullish) fields accept `null |
undefined` and default to `undefined`. We don't distinguish between null
and undefined for any of these options, so let's only accept null +
default to null. This also makes EnvironmentConfig in the playground
more accurate. Previously, some fields just didn't show up as
`prettyFormat({field: undefined})` does not print `field`.
Joe Savona
Sebastian Markbåge
lauren
mofeiZ
Andrew Clark
Zack Tanner
Niklas Mollenhauer
Ricky
Josh Story
Henry Q. Dineen
Jack Pope
Alex Hunt
Jan Kassens
Sathya Gunasekaran
Sophie Alpert